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APC BR1500G battery failure

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Robmoo

Member
Joined
Aug 18, 2005
During one of our recent rains we lost power briefly and my UPS failed. It is one of two APC BR1500g UPS. It gave me a F04 error which is bad battery or a bad UPS. I pulled the battery from mine and replaced it with the battery from my wife's and the UPS functioned fine. I put the suspected bad battery in my wife's and the battery didn't. The battery was only 18 months old so I contacted APC and even though the warranty was only a year they are sending a replacement. They asked that I simply dispose of the bad battery pack in an appropriate manner. So I took it apart. The battery pack has 2 9ah 12 volt sealed lead acid batteries. I tested the voltage of both batteries and they were both 13.2volts. I tested the wires they were connected with in the pack with my multimeter and the wires and connectors were fine. I put everything back together and put it back in both UPS and both registered the battery pack as bad. I connected both batteries my smart charger and it says that they are full.

Any ideas on why this battery pack won't work? I tested the good battery pack and it registers 27.0-26.8 volt while the rejected one registers 26.6=26.4 volts. I wouldn't think that the slightly lower voltage would make a difference. Since both batteries have exactly the same voltage I wouldn't think that any of the cells in either are going bad.
 

RollingThunder

Destroyer of Trolls & Spammers
Joined
Jan 7, 2005
Perhaps when under a load it fails? Similar to a car battery that shows good when not under a load but when cranked it fails. Just a guess.....
 

larrymoencurly

Member
Joined
Jul 14, 2002
Test under load, like 10% of the amp-hour rating, or about 0.9 amp. A 12V incandescent bulb made for cars will work as a load, but don't use headlights because they draw several amps. Measure both the voltage with no load and the voltage after the 1 amp load has been applied for several seconds.